2-1/2 inch Black Iron Union Female x Female

2-1/2 inch Black Malleable Iron Union – Threaded Fitting for High-Demand Mechanical Systems

The 2-1/2 inch Black Malleable Iron Union is a threaded pipe fitting used to connect two sections of male-threaded pipe, allowing for future disassembly and maintenance without cutting. Designed for use in low- to medium-pressure applications, this union enables secure mechanical joining of iron piping systems and is suitable for fuel gas, air, steam, and non-potable water lines.

Its three-piece construction consists of two female-threaded ends and a central nut, which draws the mating halves together and creates a pressure-tight seal when used with proper thread sealant. The union’s malleable iron body is coated with a black oxide finish, making it suitable for interior installations where corrosion protection is not required beyond surface treatment.

Product Features

• ✅ Threaded Connections — Female NPT threads manufactured to ASME B1.20.1 for compatibility with standard pipe threads.
• ✅ Malleable Iron Construction — Conforms to ASTM A197 for strength and pressure-handling capacity in demanding mechanical systems.
• ✅ Serviceable Joint — Facilitates disassembly and component replacement in gas, steam, or mechanical systems without disturbing adjacent pipework.
• ✅ Heavy-Duty Design — Built for large-diameter pipe transitions in commercial, industrial, and process piping installations.

Technical Specifications

• Nominal Size: 2-1/2 inch
• Material: Black Malleable Iron
• Connection Type: NPT Female x NPT Female (Union Nut Style)
• Standards: Complies with ANSI/ASME B16.3 and B1.20.1, ASTM A197, and typically listed under UL/FM for applicable systems
• Pressure Rating: 150 PSI Steam; 300 PSI Water, Oil, Gas (WOG)

Common Applications

Used in large-diameter pipe runs within commercial gas distribution, hydronic heating circuits, process piping, and low-pressure steam systems. Provides a removable connection point for maintenance, inspection, or retrofitting in heavy-duty mechanical environments.

Installation Guidelines

Install with compatible thread sealant (PTFE tape or thread compound) to ensure leak resistance. Proper alignment is critical during assembly to prevent thread damage or leaks under load. Tighten union nut securely to compress mating faces and ensure uniform sealing contact.

The 2-1/2 inch Black Iron Union is engineered to support safe and accessible system design in large-scale mechanical piping. Its reusability, pressure rating, and conformity to recognized plumbing and mechanical standards make it an essential component for professionals working in gas, steam, and structural piping environments.